hbase-protocol/src/main/java/org/apache/hadoop/hbase/util/ByteStringer.java

   1 /**
   2  * Licensed to the Apache Software Foundation (ASF) under one
   3  * or more contributor license agreements.  See the NOTICE file
   4  * distributed with this work for additional information
   5  * regarding copyright ownership.  The ASF licenses this file
   6  * to you under the Apache License, Version 2.0 (the
   7  * "License"); you may not use this file except in compliance
   8  * with the License.  You may obtain a copy of the License at
   9  *
  10  *     http://www.apache.org/licenses/LICENSE-2.0
  11  *
  12  * Unless required by applicable law or agreed to in writing, software
  13  * distributed under the License is distributed on an "AS IS" BASIS,
  14  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  15  * See the License for the specific language governing permissions and
  16  * limitations under the License.
  17  */
  18 package org.apache.hadoop.hbase.util;
  19
  20 import com.google.protobuf.ByteString;
  21 import com.google.protobuf.HBaseZeroCopyByteString;
  22
  23 import org.apache.yetus.audience.InterfaceAudience;
  24 import org.slf4j.Logger;
  25 import org.slf4j.LoggerFactory;
  26
  27 /**
  28  * Hack to workaround HBASE-10304 issue that keeps bubbling up when a mapreduce context.
  29  */
  30 @InterfaceAudience.Private
  31 public final class ByteStringer {
  32   private static final Logger LOG = LoggerFactory.getLogger(ByteStringer.class);
  33
  34   /**
  35    * Flag set at class loading time.
  36    */
  37   private static boolean USE_ZEROCOPYBYTESTRING = true;
  38
  39   // Can I classload HBaseZeroCopyByteString without IllegalAccessError?
  40   // If we can, use it passing ByteStrings to pb else use native ByteString though more costly
  41   // because it makes a copy of the passed in array.
  42   static {
  43     try {
  44       HBaseZeroCopyByteString.wrap(new byte [0]);
  45     } catch (IllegalAccessError iae) {
  46       USE_ZEROCOPYBYTESTRING = false;
  47       LOG.debug("Failed to classload HBaseZeroCopyByteString: " + iae.toString());
  48     }
  49   }
  50
  51   private ByteStringer() {
  52     super();
  53   }
  54
  55   /**
  56    * Wraps a byte array in a {@link ByteString} without copying it.
  57    */
  58   public static ByteString wrap(final byte[] array) {
  59     return USE_ZEROCOPYBYTESTRING? HBaseZeroCopyByteString.wrap(array): ByteString.copyFrom(array);
  60   }
  61
  62   /**
  63    * Wraps a subset of a byte array in a {@link ByteString} without copying it.
  64    */
  65   public static ByteString wrap(final byte[] array, int offset, int length) {
  66     return USE_ZEROCOPYBYTESTRING? HBaseZeroCopyByteString.wrap(array, offset, length):
  67       ByteString.copyFrom(array, offset, length);
  68   }
  69 }